Pilot for valve seating cutters



May 29, 1934.

G. M. GRAHAM PILOT FOR VALVE SEATING CUTTERS Filed Oct. 7, 1931 I! 8 I Iv I: I:- 11 t INVENTOR eavyew. 6722 ATTO RNES- Patented May 29, 1934George M. Graham, Detroit, Mich, assignor to Kent-Moore Organization,Detroit, Mich, a corporation of Michigan Application October 7, 1931,Serial No. 567,462

1 Claim.

This invention relates to aligning pilots and more particularly to suchdevices especially adapted for use in connection with cutting tools forforming valve seats of internal combustion engines and other deviceswhere great accuracy is required.

An object of the invention is to provide a pilot of simple constructionwhich is cheap to manufacture, accurate in operation and easy tomanipulate, and wherein the construction is such as to make the deviceself expanding, automatic and accurate in alignment, and that may bereadily and quickly inserted in a valve stem guide to accurately holdand guide a valve seat cutting tool during the forming or re-forming oithe valve seat.

With the above and other ends in view, the invention consists in thematters hereinafter set forth and more particularly pointed out in theappended claim, reference being had to the accompanying drawing inwhich- Figure 1 is a side elevation of the pilot de- .tached and shownpartly in longitudinal section;

Fig. 2 is a transverse section substantially upon the line 2-2 of Figure1;

Fig. 3 is a view similar to that of Figure l and showing a slightlymodified construction;

Fig. 4 is an end elevation of Figure 3; and

.Fig. 5 is a View of a portion of an engine in section, and illustrativeof the manner in which the pilot embodying the present invention isadapted to be used in re-forming the engine valve seat by means of asuitable cutting tool guided by said pilot.

In forming or re-forming the valve seat 1 of an internal combustionengine, this seat must be in exact axial alignment with the valve stemguide 2, as otherwise the valve would not properly seat, and to insuresuch accuracy a pilot is inserted in the bore of the valve stem guidewith its upper end portion projecting upwardly through the opening inwhich the seat is formed and in exact axial alignment with said openingso that a cutter 3 may be sleeved upon this portion of the pilot andwill be held and guided thereby concentric with the valve seat duringthe forming operation, said cutter being freely rotatable upon saidpilot and arranged to be "rotated by means of a suitable handle member isleeved over the upper end of the pilot and engaged in any suitablemanner at its lower end, with said cutter, to turn the same. 7

Pilots for this purpose are commonly made for insertion in the valvestem guide and provided with means adjacent their inner ends forexpanding the same within the bore of said guide to center the pilotwithin said bore, but such expanding means is usually operated by themechanic through the medium of a member extending through an axial borein the pilot and through the upper end thereof. The pilot is thuscomplicated and weakened in its construction, and care is necessary inplacing and expanding such a pilot.

The pilot embodying the present invention and as shown in Figures 1 and2, comprises a rod which is turned to the proper diameter throughout theupper end portion 5 thereof, to fit the axial bore of the cutter 3which, in the operation of the device, is sleeved upon this end portionof the pilot, free to turn thereon, after the pilot has been inserted inthe valve stem guide. The lower end portion 6 of this pilot rod isturned down to a diameter considerably less than the internal diameterof the valve stem guide 2, and connecting these portions 5 and 6, is aportion 7 formed tapering or conical to engage within the upper end ofthe bore of the valve stem guide and seat against the inner edge thereofto accurately center the upper end of the portion 6 within said bore.

To provide for the accurate centering of the lower end of the portion 6within said bore and thus co-act with said taper 7 in holding theportion 5 of the pilot in exact axial alignment with the axis of thevalve stem guide, said end portion 6, adjacent its lower or inner end,with a bulge or enlargement 8 which, at its line of largest diameter, isof greater diameter than the internal diameter of the bore of the valvestem guide, and this enlargement is preferably tapered longitudinally ofthe end part 6, each way from the largest part of said enlargement. Theend or part 6 is bored axially inward from its free end as at 9 to apoint beyond said enlargement 8, and that part or" the tubular end thusformed and which is formed with the enlargement 8, is split or slottedlongitudinally at any desired number of places around the tube as at 10,thus dividing the tube into yieldable portions or fingers, which, whenthis tubular end is forced endwise into the bore of the valve stem guidebringing the enlargement 8 into contact with the wall of said guide,will yield inwardly. These yieldable portions thus firmly press theenlarged portions thereof into firm yielding contact with the wall ofthe bore of the valve stem guide and accurately center this inner end ofthe pilot within said bore. The inner end of the pilot is thus made selfexpanding and centering, so that it is only necessary for the mechanicto force the pilot endwise into place, and it may be removed in a likemanner without other manipulation, relieving the mechanic from thenecessity for manually or care in centering and expanding the pilot.

In Figures 3 and 4 a slightly modified construction of pilot is shown inthat the slits 10 dividing the tubular end of the pilot, are cut throughthe end of the tube as shown at 11, thus making the spring fingers ordivisions more yielding than where these slots do not extend through theend, as in Figures 1 and 2. Obviously other changes may be made withinthe scope of the appended claim, and such changes are contemplated.

Having thus fully described my invention, what I claim is:

A self positioning pilot for a valve seat cutter for use in combinationwith a valve seat and a bore co-axial with the valve seat and forming avalve stem guide, comprising a rod adapted to receive a cutter androtatably support the same, said rod being of larger diameter than saidbore, a tubular end portion of lesser diameter than said bore, a conicalportion connecting said rod and tubular end portion and adapted to seatwithin the upper end of said bore, said tubular end portion being formedintermediate the ends thereof with an arcuately tapering enlargement,said enlargement at its largest part being of greater diameter than saidbore, said enlargement being slitted throughout the length thereofradially and longitudinally to provide portions to yield inwardly uponinsertion of said enlargement within said bore and frictionally engagethe wall of the bore.

GEORGE M. GRAHAM.

